BANGKOK — Activists in Southeast Asia say thousands of people are fleeing Bangladesh and Burma by sea, resuming a seasonal migration that has seen many head south in recent years. Nearly all are attempting to illegally enter Malaysia via Thailand.

Monitors along the Burma-Bangladesh border estimate that 17,000 people have already left the area since August, mostly on big boats.

The information comes from the non-governmental organization, the Arakan Project.

Chris Lewa is the director of the research-based humanitarian group concerned with the plight of the stateless Rohingya, a minority Muslim ethnic group in the region.

“Just in the last week or so we have nearly 4,000 people who are on the move. We are particularly concerned that this season, I would say from now on during the dry season, there is going to be a massive movement of boat people,” he said.

U.N. officials in the region say they deem the reports “credible” but have no specific numbers of their own.

Economic migrants from Bangladesh and Burma have long risked dangerous sea voyages in search of better jobs in Malaysia and elsewhere in Asia. But sectarian violence between Buddhists and Muslims in Burma in the past year has led to rising numbers of ethnic Rohingya fleeing the country.

U.N. organizations have noted the shift this year to larger vessels from the small and dangerous older fishing vessels previously used by the Rohingya in the Bay of Bengal.

Lewa tells VOA the more sophisticated exodus appears to be well organized. “This cannot exist, this kind of thing, without close collaboration with authorities in the country, whether it is Thailand or in Bangladesh. But specifically in Thailand all this movement of people, I think, cannot happen with some connivance,” he stated.

The Thai online news site Phuketwan said would-be refugees and villagers on the country’s western Andaman coast have fingered renegade Thai officers who are participating in people smuggling.

The Reuters news agency, in July, reported that interviews with people smugglers and survivors of boat voyages, revealed some Thai naval security forces were working “systematically with smugglers to profit from the surge in fleeing Rohingya.”

Lewa says her contacts along the border note that people in Burma are boarding ferry boats in daylight and without paying authorities, suggesting at least an informal “open door policy” by the country for those Muslims desiring to leave.

The passengers are transferred among ships in international waters, according to witnesses who spoke with Lewa. They are reportedly held in makeshift camps built by smugglers in southern Thailand until they can pay $2,000 per person to be moved across the border into Malaysia.

“There is a lot of concern that if they can’t pay they may be sold or trafficked. It is difficult, of course, to find evidence of this but we do believe that there are people being sold to fishing trawlers or plantations, either in the south of Thailand or Malaysia,” stated Lewa.

The U.N. Refugee Agency said it has noted that since inter-communal violence last June in Rakhine state, more women and children are fleeing. Previously it was primarily men who risked their lives by taking perilous journeys on smaller boats.

Several small overcrowded boats carrying about as many as 200 Rohingya capsized and sank in rough seas in May of this year off the coast of western Burma. Fewer than one third of those on board made it ashore.

Marine police in Satun province, in far southern Thailand, confirm that 219 Rohingya swam to a beach after their vessel ran aground on a sandbank on September 11. The men were given drinking water and fuel, their boat was pushed back out to sea and they were sent on their way towards Malaysia, marine police Lt. Gen. Bungerd Manawat told VOA.

The maritime migration of the Rohingya is considered one of the biggest movements of boat people since the end of the Vietnam War in the mid-1970’s.